package com.zueb.web.servlet;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

/**
 * 生成验证码的Servelt
 * 验证码其实就是一张图片，所用到的核心技术就是AWT绘图.AWT属于Java SE的核心内容
 */
@WebServlet(name = "CheckCodeServlet", value = "/CheckCodeServlet")
public class CheckCodeServlet extends HttpServlet {

    private static final long serialVersionUID = -8112015860301637701L;

    private Font mFont=new Font("Times New Roman", Font.PLAIN,18);//设置字体
    //static String AuthCode="";// 处理post

    public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {
        // 取得一个1000-9999的随机数

        HttpSession session=request.getSession();//request.getSession(false)当参数为false时，有可能不创建session //session.setAttribute("getImg",s);
        //设置Servlet返回的是图形的内容
        response.setContentType("image/gif");

        //防止缓存
        response.setHeader("Pragma","No-cache");
        response.setHeader("Cache-Control","no-cache");
        response.setDateHeader("Expires", 0);

        //要生成的验证码图形的宽度和高度（默认）
        int width=60;
        int height=20;

        if(request.getParameter("width")!=null && !request.getParameter("width").equals(""))
            width = Integer.parseInt(request.getParameter("width"));
        if(request.getParameter("height")!=null && !request.getParameter("height").equals(""))
            height = Integer.parseInt(request.getParameter("height"));

        //产生Servlet的输出流
        ServletOutputStream out=response.getOutputStream();

        //设置图片大小的
        BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        Graphics gra=image.getGraphics();
        //设置背景色
        Random random=new Random();gra.setColor(getRandColor(200,250));
        //设置字体色
        gra.fillRect(0,0,width,height);gra.setColor(Color.black);
        // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
        gra.setFont(mFont);
        gra.setColor(getRandColor(160,200));
        for (int i=0;i<155;i++)
        {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            gra.drawLine(x,y,x+xl,y+yl);
        }

        // 取随机产生的认证码(4位数字)
        String sRand="";
        for (int i = 0;i < 4;i++){
            String rand=String.valueOf(random.nextInt(10));
            sRand+=rand;
            // 将认证码显示到图象中
            gra.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
            //调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
            gra.drawString(rand,13*i+6,16);
        }
        //System.out.println("showimage="+sRand);
        //session.setAttribute("getImg",sRand);
        //将验证码放入session
        session.setAttribute("checkCode",sRand);
        //AuthCode = sRand;
        //session.putValue("AuthCode",sRand);
        JPEGImageEncoder encoder= JPEGCodec.createJPEGEncoder(out);
        encoder.encode(image);//out.flush();
    }


    static Color getRandColor(int fc,int bc){//给定范围获得随机颜色
        Random random = new Random();
        if(fc>255) fc=255;
        if(bc>255) bc=255;
        int r=fc+random.nextInt(bc-fc);
        int g=fc+random.nextInt(bc-fc);
        int b=fc+random.nextInt(bc-fc);
        return new Color(r,g,b);
    }


    static public String getAuthCode(HttpSession session){//返回验证
        return (String)session.getAttribute("checkCode");
    }


    public void init() throws ServletException {
        // Put your code here
    }

}
